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(C) According to the Doppler effect,when an observer moves with velocity $V_1$ towards a stationary source,the apparent frequency $F_1$ is given by: $

Vedclass · Accepted Answer

$3$

Vedclass · Answer

(C) According to the Doppler effect,when an observer moves with velocity $V_1$ towards a stationary source,the apparent frequency $F_1$ is given by: $F_1 = F_0 \left( \frac{v + V_1}{v} \right)$,where $F_0$ is the actual frequency of the source.When the observer moves away from the stationary source with velocity $V_1$,the apparent frequency $F_2$ is given by: $F_2 = F_0 \left( \frac{v - V_1}{v} \right)$.Given the ratio $\frac{F_1}{F_2} = 2$,we have: $\frac{F_0 \left( \frac{v + V_1}{v} \right)}{F_0 \left( \frac{v - V_1}{v} \right)} = 2$.This simplifies to: $\frac{v + V_1}{v - V_1} = 2$.Cross-multiplying gives: $v + V_1 = 2(v - V_1) = 2v - 2V_1$.Rearranging the terms: $3V_1 = v$.Therefore,$\frac{v}{V_1} = 3$.

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